Continuous strands of fibrous material, such as glass filaments, have been collected and distributed using opposed Coanda effect surfaces to produce mats of such material used, for example, for insulation. Examples of such equipment are disclosed in U.S. Pat. Nos. 4,300,931; 4,466,819; and, 4,496,384. Such continuous strands typically are handled wet since they are coated with binder or sizing which is sprayed or otherwise applied to the strands prior to the strands being passed to the Coanda effect surfaces.
Unlike these continuous fibers, chopped fibers are dry such that there can be a substantial build up of static electricity during their processing. Accordingly, when chopped fibers are handled, equipment for suppressing or dissipating static electricity is normally provided. Unfortunately, static suppression equipment adds expense to equipment handling dry chopped fibers and can cause problems of its own in terms of maintenance.
Even so, non-woven webs of bonded chopped glass, i.e., chopped strand mat, have been produced for many years. An initial step in that production is to collect the chopped glass and deposit it onto a moving collection surface with the resulting mat of chopped glass being processed to produce the chopped strand mat. Choppers are positioned over a forming hood which surrounds the collection surface with the choppers providing chopped glass to the forming hood through openings in the top of the hood to direct a chopped glass stream toward the collection surface. Air nozzles are angled into the glass stream in an attempt to disperse the glass stream.
The amount of glass strand input to each of the choppers is adjusted and the nozzles bent in an attempt to evenly distribute the chopped glass on the collection surface. The collection surface is foraminous and has air drawn through it to assist in the even distribution of the chopped glass and to draw the glass to the collection surface. Unfortunately, these efforts to achieve uniform fiber distribution on the collection surface are not always successful.
There is, thus, a need for improved apparatus for collecting chopped fibers from a source of such fibers and depositing the chopped fibers on a collection surface such that the chopped fibers are evenly distributed and thereby better able to be processed into chopped strand mat. Preferably, such apparatus would overcome problems with turbulent air flow in the forming hood and static electricity which are associated with existing chopped fiber handling.